Use the Oil Can to repair the clock in Diamond Plains. Go to the right and jump up onto the clock tower. Go inside (the entrance is next to the guy repairing it). Work your way to the right and then up and over. You’ll need to click on the rope pulleys to drop the red iron girders so that you can pass. Once you make it all the way through, use the oil in your backpack to loosen up the gears. Click on each gear inbetween the two main gears and drop just enough oil so that each one is sparkly-clean. Then click on the turn gears button in the lower-right and the clock will be fixed!
How to Get the Oil Can
Once you get the Gold Nugget, there’s no need for you to keep the Gold Pan, so go back to the Dusty Gulch and go inside the Trading Post again. Now trade the gold pan for the oil can.